Telescriber



Aug-8,19% w. A. LAUDER ETAL 2,355,087

TELESCRIBER Filed Aug. 2, 1941 1o Shgets-Sheet 1.

INVENTORS VlQz/lace A. Lauder BY Edward CahoonQ d- ATTORNEYS Aug. 8, 1944. I w. A. LAUDER 'VETAL- TELESCRIBEIR 10 Shets-Sheet 2 VENTORS 1 772191106 A. Lau BY Edward Ca a fi g r v Au g. 8, 1944. w. A. LAUDER ETAL TELESCRIBER Filed Aug. 2, 1941 10 Sheets-Sheet 3 w. A. LAUDER ETAL 2,355,087

TELESCRIBER Aug. 8, 1944.

10 Sheets-Sheet 4 Filed Aug. 2, 1941 )9VENTORS- W51 ace BY Edward If Ca fl. Lauder r 4 W. A. LAUDER ET AL 2,355,087

' TELESCRIBER l0 Sheets-Sheet 5 -|NVENTORS Wallace JLLauder BY Edward I. (Ia/"won ATTORN EY Aug. 8, 1944.

w. A. LAUDER ETAL TELESCRIBER Filed Aug. 2, 1941 l0 Sheets-Sheet 7 ah m E M ww m a WW M,

Aug. 1944- w. A. LAUDER ETAL 2,355,087

TELESCRIBER Filed Aug. 2, 1941 10 Sheets-Sheet 8 Q g Q Q 1'. "i: (I) r & lli'ln. R2

8 Q N INVENTORS Wallace A. Lauder Edward 061110017.

Aug. 8, 1944.

Filed Aug. 2, 1941 w. A. LAUDER ETAL. 2,355,087

TELESCRIBER l0 Sheets-Sheet 9 l VENTORS Wa ace A. Lauder BY Etiwlll'd 1 G G-k002i Patented Aug. 8, 1944 TELESCRIBER Wallace A. Lauder, Closter, and Edward F. Ca-

hoon, Tenafly,'N. J., assignors to Telautograph Corporation, New York, N. Y., a corporation of Virginia Application August 2, 1941, Serial No. 405,226

25 Claims.

This invention relates to improvements in methods and apparatus for instantaneously transmitting facsimiles of the traces of graphic characters from one location to another.

Certain forms of such apparatus, known as writing telegraphs or telescribers, have in the past been proposed for accomplishing the purposes of this invention. Although only one type of such apparatus has proved to be commercially feasible, this type of telescriber has been in satisfactory commercial operation for almost half a century. It operates by developing two direct current voltages, each of which varies with the variation in the coordinates of the position of a stylus tracing the graphic characters to be transmitted. These two' direct current voltages, usually obtained from movable taps on resistive potentiometers connected across a D. C. power supply, are transmitted over suitable electric lines to distant receiver units. In the receiver units these two D. C. voltages are applied to two D. C. motors, each one responsive to a D, C. voltage which corresponds to one of the coordinates, to drive suitable linkage systems which move a pen over a writing surface, usually a strip of paper positioned beneath the pen, to reproduce a facsimile of the graphic characters transmitted.

, With the increasingly widespread use of alternating current power, such machines were subject to the frequent disadvantage of requiring motor generator or rectifier systems to supply them with direct current. Furthermore, such machines were ungainly in appearance due to the type and arrangement of the operating components, and inefiicient in the use and handling of the paper -upon which the graphic characters were reproduced.

Accordingly, therefore, it is an object of this invention to provide improved methods and apparatus for telescribing graphic characters, and to provide such improved telescriber apparatus capable of operating on an alternating current power supply.

It is a further object of this invention to provide telescriber apparatus having improved means for handling. the record strip upon which the graphic characters are reproduced, to provide means for improving the visibility of the message transmitted, and to provide means for more simply handling and more efficiently using therecord paper.

These and other objects and advantages of this invention, which will be in part obvious and in part pointed out hereinafter, are obtained by the means described in the following specification,

and may be more readily understood by reference to the accompanying drawings, showing one or more of the various possible embodiments of this invention, in which:

Figure 1 is a perspective view of a new and improved combined telescriber transmitter and receiver unit, embodying the invention herein described, in which the paper strip, upon which the messages sent and received are recorded, is wound up in the machine itself for future reference;

Figure 2 is a perspective view of a telescriber similar to that shown in Figure 1 but embodying a different type of message paper handling arrangement, in which the message may be torn from the machine as soon as it has been recorded; Figure 3 is a plan view of the transceiver shown in Figure 1 with portions broken away to 'show details of the transmitter stylus linkage and the message paper handling structure;

Figure 4 is a section of the machine, taken 0 line 4-4 of Figure 3;

Figure 5 is a plan view of the bottom of the machine; I

Figure 6 is a vertical section of the machine, taken on line 6-5 of Figure 4;

Figure 7 is an enlarged sectional view of the contact structure of the paper handling'mechanism, taken on line 'l-Tof Figure 6;

Figure 8 is a similar view of a portion of this same structure, taken on line 8-8 of Figure 6;

Figure 9 is a vertical section of the machine,

taken on line 99 of Figure 6;

Figure 10 is an enlarged sectional view of the stylus'interlock switch and relay structure, taken on line Ill-l0 of Figure 5;

Figure 11 is a similar view of a portion of this same structure, taken on line l'l|l of Figure 10;

Figure 12 is a skeletonized schematic perspective view of the record paper handling mechanism of the telescriber shown in Figure 1;

Figure 13 is an enlarged oblique section of a portion of the receiver section of the machine,

ratus, the local transmitter receiver 4 from 2 2,855,087 gram of the telescriber transceiver shown in Fig- Figure 1) is energized to lock the unison switch ure 1: It in "ofl. position to prevent a message being Figure 18 is a portion of Figure 17 schematically showing the paper handling mechanism' contacts in an alternative position; and

Figure 19 is a longitudinal cross-section of the record strip take-up roll, taken on line II-i1 of Figure 9. i

sent from the local transmitter 2 while the local receiver 4 isrecording a message from the dis- A brief preliminary description of the general layout and operation of the telescriber instrument embodying the invention may be helpful at the outset in order that the detailed description I following may be more readily understood. Re-

ferring to Figure 1, the telescriber transceiver,

? in accordance with this invention, comprises a transmitter portion, generally indicated at 2, and a receiver portion, generally indicated at 4, mounted on a common base in a housing member I. The transmitter portion 2 is provided with a pencil-like stylus member 8 pivotally Joined to a pair of link driving members Ill and 12 which are connected through suitable linkage mechanism (not shown in Figure 1) to operate transmitting elements, hereinafter to be described, forming part of the transmitter portion 2 housed in the casing I. The machine is put in operation by rotating with the stylus 8 a "unison" switch, generally indicated at I6, 10-

lock arrangement interconnected with the linkage, structure moved by the stylus 8 so that it I can be operated only by the stylus. A signal arrangement is provided so that, when the machine is not in operation, a signal circuit may be ac-.

"tuated by pushing a push-button It on the transmitter portion 2 to operate a suitable buzzer at a distant receiving station suitably connected to tance transmitting station.

In the telescriber shown in Figure 1, all messages transmitted by the transmitter portion 2 or received from a remote transmitter by the receiver 4 are recorded on the paper strip 22 which isunwound and rewound within the receiver housing 4 by a paper handling mechanism, hereinafter to be described. The receiver portion 4 is provided with a hinged cover 30 hinged at 33 which may be lifted to provide access to the paper strip 22 on which messages have already been recorded so that ready reference may be made to such prior messages by unwinding the strip from a paper takeup roll 3i (not shown in Figurel). A push-button 32 is provided on the transmitter portion 2 of the telescriber to operates paper irewind motor to rewind this paper after reference'has been made to such previous messages.

'cated at one corner of a transmitting platen I4. The unison switch I is provided with an interthe transmitter, thusv announcing that a message-is about to be transmitted. Similarly a suitable buzzer. i9 (not shown in Figure 1) is provided in the receiver portion 4 to be actuated when a distant transmitter wishes. to transmit to the local receiver. The operator then traces the graphic characters to be transmitted on the metal platen l4 with the styluslr In addition to being connected to a distant receiving appa- 2 is also connected to the local receiving apparatus 4 so that the operator can see the characters he is transmitting. A strip of message paper 22, fed through the machine ma manner hereinafter to be described, passes over a metal platen 23 (not shown in Figure 1)v and underneath a pen 26, and is protected by a transparent window 24 forming part of the receiving portion 4 of the machine,- as shown in Figurel. The pen 2 is suitably attached to two linkage members 21 and 28 which inturn are connected to two telescriber receiving motors (not snbwn in Figure '1) mounted in the receiver portion motors drive the pen 22 within the receiver 28 across the paper strip writing area, generally indicated at 36, to reproduce the characters traced by the operator with stylus 8 on the or the trace of characters some tion.(not-shown).

The'f'busy" lamp 20 is lighted only when a platen i4, transmitted to ,the

I remote transmitting station, connected to the 'local transceiver, isturned on 'to transmit a message to the local receiver portion 4. At the same time that busy lamp 2| is lighted an interlock relay, generally indicated at I! (not shown in 4 of the telescriber. These remote transmitting staas soon as a message is recorded on the record strip 22 in the receiver writing area 36 by the pen 26, the paper strip 22 can be shifted upwardly so that the message may be immediately detached from the machine, if desired.

In a telescriher instrument made in accordance with this invention, a message can be read as it is being written without the linkage members 21 and '28 obscuring any portion of the message because the pen 26 and its driving links 21 and 28 are always'beneath the pen 26 and the tear-ofl' strip 34. Furthermore, the message may be removed from the machine immediately it is received without wasting paper, because it is written on the end of the paper strip instead of at some intermediate place on the strip, as was necessary in the previously known telescriber instruments.

Now that, the general construction and operation of the telescriber illustrated has been deand 5, as above-mentioned, the telescriber transceiver illustratedcomprises a transmitter portion 2, which is mounted in a metal chassis or frame 38 and a receiver portion 4 mounted on a frame secured to chassis 38, and this entire assembly is contained in a housing structure 6. The stylus 8 of the transmitter portion 2 is connected by a ball-and-socket type joint 40 to one end of the right-hand stylus linkage member l2, which in turn is connected through another balland-socket type joint 42 to one end of a lever arm 44 securely fastened to a vertical shaft 46 suitably Journaled at the right-hand side of the transmitter chassis 2. The left-hand stylus link- 52 to limit the motion of the tracing end of the stylus 8 to points within a predetermined writing area on the platen I4. The upper end of the shaft 6| of the unison switch IS, a switch of the rotary-toggle type (see Figures 10 and 11) which is mounted on the top of chassi 38, is provided with an actuating arm 60 having a semi-circular concavity 62 on one side thereof into which the ball-and-socket joint 46 of the stylus 8 may be fitted to move the switch from its off position shown by the solid lines in Figure 3, to its on position shown by the dotted line. In order to prevent the unison switch l6 from being operated when the stylus is not in its neutral or unison position at the switch I6, the switch shaft 6| is provided with a circular cam member 64 having two recesses 66 and 68 cut in its periphery, as shown in the drawings. A bellcrank 10 is pivoted adjacent the cam 64 and'one of its free ends 12, shaped as a pawl to fit snugly into the recesses 66 and 68 of cam 64 when unison switch I6 i in its off or on positions, respectively, is biased toward the periphery of the cam 64 by a spiral spring 14 (see Figure 4). The other end 16 of the bellcrank 10 is bent downwardly to intercept the path of a pin 18 projecting from the lefthand vertical shaft 54. Thus, when stylus 8 is in its neutral position so that the left-hand lever 52 is in its most clockwise position, as shown in Figure 3, the pin 18 attached thereto contacts the end 16 of pawl 10 and moves it away from cam 64 in opposition to the force of spiral spring 14 to lift the pawl-like end 12 out of one or the other of the recesses 66 or 68 so that stylus 8 may be used to rotate the unison switch from one position to the other. It will be evident that for all other positions of the stylus, except the neutral position shown in Figure 3 when pin 18 contacts the bellcrank arm 16, the end 12 of the pawl 1|] will rest in one of the recesses 66 or 68 in cam 64 and thus prevent rotation of the unison switch. This structure acts as a safety lock to prevent the machin from being turned on at any time except when the stylus 8 is in neutral position. This, as will be pointed out hereinafter, prevents the receiving pen 26 from jumping from its neutral position at the lefthand side of the receiving platen 23 to some intermediate point in the receiver writing area 36 when the telescriber is energized. This prevents strain in the mechanism and eliminates any danger that the receiving pen 26 may splash ink over the recording strip 22, asmight occur should the pen be suddenly removed from its neutral position to the middle of the writing area 36. If it were not for this safety feature, this latter action might occur, because, as will hereinafter be described, when a telescriber transmitter is energized, the recording pens in all receivers connected thereto immediately assume a position corresponding to the position of -the transmitting stylus. If this position is any other than some chosen neutral position, the pens will 3 snap from their normal neutral positions to positions corresponding to the transmitter stylus position, thus endangering the pen driving mechanism and probably splashing ink over the recording strip.

Details of the contact structure of unison switch l6 are shownin Figures 10 and 11. Switch shaft 6| is journaled in a bracket 450 secured to the under side of the top of transmitter chassis 38. An arm 452, secured to shaft 6| by a. "set screw 454, carries a-to'ggle member 456 of insulating material pivoted at its outer end. The

toggle member 456 carries a pin 458 on its outer end which projects through a hole in one of a pair of leaf spring contacts 460 secured to but insulated from the bracket 450 by the usual stack construction 462. When arm 452 and toggle member 456 are in the position shown in Figure 11, the leafspring contacts 460 are separated and thus unison switch 6 is in off position. When the switch actuating arm 60 is moved by stylus 8 to its on position shown by the dotted lines in Figure 3, shaft 6| is rotated in a clockwise direction, as seen in Figure 11, moving toggle member 456 to its alternative position and closing contacts 460. Shaft 6| is also provided with a segmental arm 464, secured thereto by set screw 466, having two radially extending projections 468 which coact with a pin 410 to act as stops limiting the rotation of shaft 6| of the unison switch l6 to its off and on positions.

The interlock relay H is also secured to this unison switch structure l6. Referring to Figure 10, this relay comprises a pair of windings 412, each surrounding one leg 414, respectively, of two U-shaped magnets 416. When these windings 412, which are connected in series, are energized, in the manner hereinafter tobe described in connection with the circuit diagram of the instrument shown in Figure 1'7, they attract an L- shaped armature member 418 pivoted at 480. Movement of the armature 418 tends to pivot a crank-shaped lever 482 aboutthe pivots 480 so that its free end presses upwardly against a spring member 484 which pushes a pin 486, slidably positioned in a sleeve 488, upwardly against the segmental arm 464. If unison switch I6 is in off position this pin 486 lies under a hole 496 in arm 464 and therefore it is pushed into hole 490, locking the unison switch in off position, thus preventing the local transmitter 2 from operating while a message is being sent to the local receiver 4. This upward movement of the free end of lever 482 also opens the connection between contacts 446, one of which is secured to an insulated member 482 extending from the end of lever 482, to open the circuit to the local signalling push-button l8, as will hereinafter be described, to prevent the local operator from signalling to a distant station while the local receiver 4 is recording a message from a distant transmitter. If unison switch I6 is in on position the coils 412 cannot be energized, aswill hereinafter be described in connection with the circuit diagram of the machine shown in Figure 1'1.

In the trace of any graphic character haying discontinuities in its race, it is necessary to provide some means for lifting the receiving pen 26 from the record paper 22 whenever the stylus 8 islifted from the platen I4. In order to accomplish this, the platen I4 is made as' a separate member recessed in the upper surface of the transmitter chassis 38. It is formed of sheet metal having all of its edges l5 bent at right angles, as is best shown in Figure 9, to provide rigidity to the platen. This platen I4 is pivoted at its forward edge about a horizontal'axis across the front of the machine, on a pair of pivot screws passing through right angle brackets 82 se-- of the transmitter chassis 38 and provided with lock-nuts 84 to permit locking of the pivot screws 88 after the platen position has been accurately determined and adjusted. The back of platen I4 rests on the top of the plunger 88 of a platen switch, generally indicated at 88 in Figure 9.

. 8 is pressed onto platen I4 as a graphic character is being traced on the platen. Referring to Figure 9, the plunger 88 of the platen switch 88 is attached to one end of an L-shaped bellcrank 88 pivoted about a, horizontal axis 92. This bellcrank 98 is biased in a counterclockwise direction by means of a bias spring 98 which may be adjustably tensioned by means of a tensioning screw and nut 98. The depending end of the bellcrank 98 carries a contact I 88 which coacts with another contact I82 secured to the end of an ad- 2 justment screw I84 threaded into a suitably insulated connection post I88 in the lower portion of the platen switch 88. The limit of motion of the bellcrank 98 in a counterclockwise direction is determined by the position of contact I82, and its motion in a clockwise direction is limited by the second adjustment screw I88 threaded through another portion 'II8 of theframe of switch 88. Thus, the switch 88 is normally biased to closed contact position by the spring 98 and any pressure on platen I4, as from the stylus 8 being pressed against it when a graphic character is being traced thereon, moves the plunger 88 downwardly, rotating bellcrank 98 in a clockwise direction against the tension of spring 98, breaking the connections between contacts I88 and I82. This, as will be hereinafter described, operates the pen-lifter circuit to drop the receiving pen onto the writing surface in any telescriber receivers connected to the transmitter.

A triangularly-shaped connection board H2 (see Figure 5) is connected, for convenience, to the bottom side of platen switch 88 where it is readily accessible. to simplify the interconnection of various parts of the transmitter mechanism.

Another terminal strip, generally indicated at I, is also secured to the back of the transmitter chassis 38 to facilitate the connecting of the transmitter 2, and through the transmitter the receiver 4, to the external transmission circuits to leading to distant transmitters and receivers.

Referring to Figure 5,'which is a bottom plan view of the transceiver shown in .Figure l, the rotary control shafts 48 and 54 shown projecting into the interior of the transmitter chassis 88 at the left and right-hand sides, respectively, are the rotary control shafts shown projecting above the transmitter chassis 38 at the right and lefthand sides, respectively, in Figure 3. These control shafts 46 and 54 are connected to rotary contact arms [I4 and 'I I5, respectively, carrying roller contacts H8 at their outermost ends which make continuously variable contact with windings I23 of two auto-transformers or inductive Potentiometers, generally indicated at I" and H9. These auto-transformers III and H8 are constructed in the form of two concentric quadrants H8 and, I28 of suitable magnetic material connected at both ends to form closed magnetic circuits by yokes I24. The concentric quadrants I I8 and I28 are surrounded by windings I2I and I23. respectively. Connection strips I28 are provided between the windings I2I and I28 for suitably connecting the transformers III and H9 in the telescriber circuit, and flexible pigtail connections I28 are attached to contact arms I and I I8 to provide low resistance connections between roller contacts H8 and the telescriber circuit elements, as will be hereinafter described in connection withgthe wiring diagram shown in Figure 17. These inductivepotentiometers II! and H9 provide two A. C. voltages determined by the positions of the rotary contacts II8 on the windings I2I, each of which varies as a function of the variation in th value of one of the coordinates of the graphic character being traced by stylus 8.

A "busy relay I88, also mounted on the underside'of thetransmitter chassis 88, is interconnected with the circuit of the si nal lamp 28 so as to energize this lamp when a distant transmitter is signalling to the receiving portion 4 of the transceiver illustrated, as will-be hereinafter described.

A transmitter relay I82, also mounted onthe transmitter chassis 88, suitably interconnects and actuates the various circuit elements of the transceiver when it is energized by actuation of the unison switch I8 in the manner which will be more clearly understood when reference is made to the wiring diagram in Figure 17. The transmitter chassis 88 is also provided with a multiterminal plug I28 adapted to be inserted into a corresponding connector receptacle I31 whereby 5 th various circuit elements of the receiver portion 4 of the transceiver are-connected to the transmitter portion 2 and thence to the external lines connected to terminal strip I, so that the receiver portion 4 of the transceiver may be detached and completely disconnected from the a transmitter portion 2. if desired.

Referring to Figures 4. 5, 6, 9. 12, and 13, the receiver portion 4 of th transceiver is comprised essentially of two receiver pen driving; motors, generally indicated at I88 and I82, which convert the two variable A. C. voltage signals received-from the transmitting potentiometers II! and H8 into rotary mechanical motions, which motions are combined through the linkages 21 and 28 (see Figure 1) to move the pen 28 to trace on the paper record strip 22 the graphic characters being transmitted. The receiver 4 also includes a pen-lifter mechanism, generally indicated at I84, for lifting the pen whenever a discontinuity occurs in the trace of the graphic character being transmitted, and a paper han- Y dling mechanism, shown in skeletonized diagrammatic perspective in Figure 12, for moving the paper strip 22 through the machine in predetermined increments.

All'of the elements of the receiver portion 4 are portion 4 of the transceiver can be disconnected and removed from'the transmitter portion 2.

The receiver motors I88 and I82 are bolted to oblique angle brackets I'Iland I12 secured at either end of the longitudinal frame members I88 and I88. The upper arms of these brackets I10 and I12 slope rearwardly at an angle which determines the slope of th writing platen 23 and the paper record strip 22, and therefore the slope of the front of the receiver portion 4, because the linkages 21 and 28 and the pen 26 are so secured to these motors that they move in a plane perpendicular to the drive shafts of these motors. The rest of the receiver mechanism is secured to two.vertical parallel frame members I16 and I18 provided with suitably angled brackets I80 and I62 which are bolted to the rear faces of the motors I50 and I52 so as to hold the plates I16 and I18 vertically and parallel to each other at the rear of the machine, as can best be seen in Figures 4 and 6. Most of the paper handling r plan view of the writing mechanism of the receiver 4 taken in the direction of arrows I3-I3 in Figure 4, the pen driving motors I50 and I52 are reluctance torque motors with specially shaped rotors I96 designed to produce a linear relationship between the magnitude of the applied A. C. voltage and the angular position of the rotor when working against a load whose torque varies inversely with the angular position of the rotor. As can best be seen in.the crosssectional view of motor I52 shown in Figure 14, these motors have a rectangularly shaped magnetic field structure I84, preferably made of laminated silicon steel and held together by clamping frame plates I99 clamped together through bolts 200. One side of the magnetic field structure I84 is provided with an air gap I86, thus forming pole pieces I90 on either side thereof. Field coils i88, wound around these pole pieces I90, are connected in series across the lines from the transmitter, as will be hereinafter described in connection with the wiring diagram of the instrument shown in Figure 1'7. The faces I92 of the pole pieces I90 are concave in shape to receive the rotor I94. The rotor I94 is made of a stack of laminations of suitable magnetic material. such as silicon steel, clamped together and suitably secured to a motor drive shaft I96 which shaft is suitably journaled in bearing plates I98 secured to studs extending from the clamping plates I99 of the field structure I84 parallel to the pole pieces I90*as above described. The rotors I94 are given a perdetermined shape, for example that shown in Figure 14, so as to provide the motor with a straight line characteristic relationship, as above-mentioned. A spiral spring 202 s provided to bias shaft I96 to a normal position such that the rotor I94 bears the relationship to the pole faces I92 shown in Figure 14 and to provide a torque opposing rotation of the rotor I94. One end of the spiral spring 202 is secured to a collar 204 attached to the shaft I96 by means of a set screw 206,'and the other end is clamped to a right angle bracket 208 which is adjustably secured to the front bearing plate I98 b means of a nut 2I0 threaded onto a bearin sleeve 2I2 secured to the bearing plate I98; as may be more read ly seen in Figure 16, which shows an enlarged view of this construction. Bracket 208 is suitably angularly positioned with respect to bearing plate I98 so as to position the rotor I94 in its normal angular position with respect to the polefaces I92, as shown in Figure '14.

A collar 2 I4 is attached to shaft I96 by means of aset screw 2I6 so that the shaft I96, and therefore the rotor I94, may be suitablypositioned longitudinally with respect to the field structure I84. In order to provide means for adjusting the length and therefore the torque of spring 202, a clamping arrangement is provided on the bracket 208- for clamping the spring 202 to accurately determine its active length. This clamping means comprises a bolt 2I8 passing through the bracket 208 and having a hole 220 in one end thereof through which the end of the spring 202 passes. A nut 222 is, threaded onto the bolt 2I8 onthe other side of the bracket 208 whereby any portion of the end of the spring 202 can be clamped against the bracket 208. In operation, when the field coils I88 are energized, the rotor I94 of the reluctance motor thus formed, due to its configuration, tends to rotate in the direction shown by the arrow in Figure '14 in an effort to reduce the air gap between the pole faces I92 and the periphery of the rotor I94, and thus reduce the reluctance of the magnetic circuit I84. This rotation, however, is opposed by spring 202, and therefore the angular rotation of the rotor is a function of the value of the voltage across the coils I88 and increases'as this voltage increases. In the embodiment shown, the special form of the rotor I94 causes this increase to be linear with respect to voltage.

Referring to Figure 13, the shafts I96 of the receiver reluctance motors I50 and I52 are connected, respectively, through vibration damping hubs, generally indicated at 224, flat resilient metal strips or links 226 and 228, mounted edgewise, and pivots 230 and 232, to the pen moving links 21 and 28 which are pivotally joined at 234 at the point where the pen 26 is attached to the link 28. Inasmuch as A. C. is applied to the coils I88. of the-motors I50 and I52, an oscillation of double the frequency of the A. C. voltage is produced in the shaft I96. This oscillation or nascence is helpful-in overcoming the static friction of the motors and the pen linkage systern, but its magnitude may be so great as to cause the pen 26 to make an oscillatory line instead of a smooth curve in tracing the graphic character being received. The vibration damping hubs 224 and the resilient metal links 226 and 228 are provided to attenuate this vibration between the motor shaft I96 and the pen 26.

The specific construction of the vibration-- damping hubs 224 can be more readily seen in the enlarged cross-section shown in Figures 15 and 16. A flange member 225 is secured to shaft I96 by a set screw 221. This flange member 225 is provided with four projections 229 forming. a cross-shaped recess in the outer face of the flange, as shown in Figure 15. The fiat metal link 226 terminates in a rectangular block of metal 23I provided with a hole 233 in the center thereof which fits over a pin 236 projecting from the end of shaft I96. Two resilient metal strips 238 are formed in the shape of T-shaped springs and slipped into the recesses formed by the pro-.

26 to overtravel, oil dashpots 248 are connected to the pin linkage system. Referring to Figure 13, each of these dashpots 248 is formed of'a metal cylinder 250 within which is positioned a piston-like member 25: attached to a piston rod 264, the end of which is pivotally secured at 256 to a wire lever arm 258 projecting from the end of the metal hub block 281 opposite the end to which the flat linkage member 226 is secured, as

can best be seen in Figure 15. In addition, these oil dashpots 248 also provide additional damping to prevent the A. C. oscillations of the motors from producing unwanted motion of the pen 26.

As in the case of the transmitter portion 2 of thetransceiver, stops 266 and 262 are provided in the receiver portion 4 to contact linkage members 226 and 228, respectively, at one end of their range of motion, when the rotors I84 are in'their normal position shown in Figure 14, to normally hold the pen in its neutral or unison" position shown in Figure 13. Thus, the pen 26 is normally I held in the same position with respect to the receiver writing area 36 thatthe stylus 8 assumes with respect to its writing platen I4 when the stylus 8 is positioned at the unison switch I6,

as shown in Figure 3.

In the embodiment shown, the pin 26 writes with a fluid ink which is stored in a reservoir 266 (see Figure 6), connected by a tube 268 to a small aperture 216 located at the neutral or unison position on the receiver. Thus, the pen is dipped into the hole 216 and filled by capillary action each time the pen 26 rests in the unison position, i. e., each time the transmitter stylus 8 is returned to the unison switch I6 and operates it to "oil" position.

As above-mentioned, the receiver 4 is provided with a pen-lifting arrangement I 54 for lifting the pen from the platen 23; that is to say, from the paper strip 22 passing over this platen, whenever a discontinuity occurs in the trace of the graphic character being transmitted. Referring to Figures 6, 7, 9, and 13, this pen-lifting mechanism I54 comprises two series-connected electromagnets 212 provided with a magnetic yoke 214 connecting their upper ends and mounted on the back of the platen 28 to form a U-shaped magnetic circuit with an air gap at the bottom.

The free ends of a U-shaped armature supporting bracket 215 are pivoted on pins216 at each side of the yoke 214 at the top of the electromagnets 212. An armature 218 is secured to the base of this U-shaped bracket 215 and depends adjacent the air gap of the U-shaped magnetic structure formed by yoke 214 and electromagnets 212, as shown in Figure 9. The armature supporting member 215 is so shaped and the pivot pins 216 are so positioned that the armature 218 normally is positioned slightly to the rear of the air gap at the bottom of the electro-magnets 212.

The armature supporting member 215 also. carries a horizontal cross bar 286 at its lower end. Two forwardly projecting wire members 282, bent as shown in'Figure 7, are secured to either end of the cross bar 288 by means of collars 284 and set screws 286. These forwardly projecting members 282 pass through slots 286 in the platen member 23 and support a horizontal knife-edged cross bar 282 which passes under the pen links 21 and 28 along the lower edge of the writingarea 36 of the platen 28 and is of sufllcient length to be under these links 21 and 28 regardless of the position of e pen 26 over the platen". This pen-liftin bar 282 is 'so secured to the horizontal cro bar 266 attached to the armature supporting member 2160f the pen-lifter wwrela iy that it does not contact the pen driving linkage arms 21 and 28..when the pen is moving over the platen surface 23 as long'as the magnets 212 are energized, the armature is pulledforwardly so that the armature supporting member 216 moves counterclockwise, as shown in Figure 9, about the pivots 216'until the armature 218 is immediately beneath the pole tips of the electro-magnets 212. This motion of the armature 218 is suflicient to move the pen-lifting bar 282 forwardly so that it lifts the pen 26 from the platen 23 regardless of the position of the pen with respect to the platen.

As above-mentioned, the transmitter portion 2 is provided with a platen switch 88, normally closed but which opens when the stylus 8 is pressed against the platen I4 to trace a graphic character to be transmitted. As will hereinafter be described, opening the platen switch 88 by this stylus pressure opens the circuit connected to the windings of the electro-magnets 212 of the penlifter relay I64 in the receiver 4. When the machine isenergized, this circuit is normally closed and therefore these windings arenormally energized, thereby holding the armature 218 in its forward position and thus the pen-lifter bar 282 in its most advanced position so that the pen 26 is normally held above the surface of platen 23. However, when writing commences at the transmitter station by pressure of the stylus 8 on the platen I4, thus opening the platen switch 88, this circuit to the windings of magnets 212 is deenergized and the armature 216 falls away from its forward'position pivoting about the pivots 216, thus pulling the pen-lifting bar 282 to its retracted position and lowering the pen 26 onto the paper strip 22 passing over the platen 23 so be recorded thereon.\

The receiver portion 4 of the transceiver also includes paper handling mechanism for feeding the record strip 22 from a supply roll 284 through the machine over the platen 23 past the window 24 and to the wind-up roll 3| for storing the received and .transmitted messages. This paper handling mechanism is designed to advance the strip 22 in increments equal to the height of the platen 23 so that, after a complete message is written on the platen by the pen 26, the pen is returned to the neutral or "unison" position, and the machine is deenergized by moving unison switch to of! position, the entire message is moved up out of the writing area 36 by a single operation of the paper handling mechanism. This instantly clears the writingarea 36 as soon as transmission is completed and still permits the message or character being transmitted to be instantly viewed in its entirety. ,In addition, in the embodiment shown, the paper handling mecha-. I

nism is provided with a rewinding mechanism, whereby any length of the record strip 22 wound on the rewind roll 3| may be unwound to refer to so e earlier message and automatically rewound pushing button 32 on the front of the machine.

The major portion of the paper handling mechanism is mounted behind the platen 23and between the two parallel vertical frames I16 and I18, as shown in Figures-8 and 9, but its essential details and principle of operation'may be more readily understood by referring to Figure 12,

which shows a skeletonizeclperspective of the principal elements of this paper handling mechanism. The supp y roll 284 (not shown in Figure 6) is mounted on a shaft 286 rotatably supported be ween the vertical frames I16 and I18 by U- shaped brackets 298 secured thereto. From this supply roll 294 the record strip passes through an elongated rectangular funnel-like record guide 300 made of sheet metal which guides the record strip 22 in a smooth curve around an acute angled bend 302 under a lower horizontal guide member 308, over the platen 23 between two rollers304 and 306 forming part of the record strip shifting mechanism hereinafter to be described, so that its edges pass under two vertical guide strips 3! and under an upper guide strip 3 I 2. These guide strips 308, 3I0, and 3I2 cause the record strip to lie flat on the platen 23 to present a smooth flat surface to-the. pen 26. From the upper guide strip 3I2 over the platen 23, the record strip passes upwardly over a supporting plate 3I4 behind the window 24 so that the messages transmitted or received can be clearly read by the operator, over 'a curved guide plate 3I6 in the top of the machine under the hinged top 30, and thence downwardly through a slot 3I9 (see Figure 3) in the back of the top of the machine housing 6 to the paper wind-up roll 3| suitably rotatably supported between the vertical frame plates I16 and I18. The curved upper guide 3I6 is provided with two cut-out portions 3l1, as may be seen more distinctly in Figure 3, in which the hinged top 30 is shown in its raised position and the paper record strip 22 is shown partially broken away, whereby the paper strip 22 may be lifted to unwind it from the wind-up roll 3| so that the operator ma refer to a previous message if desired.

As above-mentioned, the paper handling mechanism is provided with a paper shifting arrangement which advances the paper strip 22 in increments exactly equal to the hei ht of the platen 23. Referring especially to Figure 12, a paper shifter motor, generally indicated at 320, is mounted on the receiver cndbracket I62 (see Figures 4, 5, and 6) and, through a clutch, generally indicated at 322, a shaft 324, worm gear 326, pinion 328, and a shaft 333. drives a rubber covered paper shifter roller 304 which is positioned behind the platen 23 and presses against the under side of the record strip 22 through an aperture 332 in the platen 23. The paper shifter motor 320 is so designed that its armature 334 normally drops below its operating position between the pole faces 33: when the motor is deenergized. When the motor is energized, the.

armature is immediat ly lifted to its normal operating position directly between the poles 336 by the magnetic pull of these poles on the armature. This upward motion of the armature 334, on energization of the motor 320, engages the clutch 322. The driving element of the clutch 322 comprises a disc 338 secured to the end of the driva shaft 340 of the motor 320. Two pins 342 proiect perpendicularly from this disc at diametrically opposite points near the periphery of the disc. The driven member of the clutch 322 comprises a collar 344secured to the end of the driven shaft 324 and provided with two pins 346 secured to and extending radially from this collar 344. When the motor 320 is energized and its armature 334 moves upwardly to its operatingposition, he disc 33'8 moves upwardly so that its pins 3 2 engage pins 346 in the collar 344 and thus engage the clutch so that the motor 320 rotates the paper moving roller 304 through shaft 324, gears 326 and 328, and shaft 330. Thus it can be seen that the motor 320 and clutch 322 provide a positive and exact drive of the paper shifting roll -304.- The clutch 322 cannot slip, and there is no possibility of an overrun of the paper drive roll 304 because the instant the motor 320 is deenergized the clutch 322 is disengaged, it being impossible forthe motor armature .334 to remain in its upper position when the magnetic attraction of the pole pieces 336 is removed.

In order to insure positive traction of the rubber covered paper drive roll 304 on the paper strip 22, a serrated metal roller 306 is mounted in front of the paper strip 22. This roll 3% is pivotally mounted on a lever 348 .which is secured to a shaft 350 suitably journaled in the motor supporting brackets I10 and I12 at either side of the platen 23 and extending across the bottom thereof, as shown in Figure 13. The lever'340 is biased to rotate toward the back of the machine to hold the serrated metal roller 306 against the paper strip 22 to push it against the rubber covered roll 304 by means of a long coiled torsion spring 352. one end of which is attached to the lever 348 and the'other to the motor supporting bracket I10. In order to remove the pressure of the roll 303 when paper is initially threaded into the machine after a new paper supply roll 294 has been pvt in place, a lever 354 secured to the lefthand end of the shaft 350 extends downwardly to a pivotal connection with a second lever' 356 which extends to the rear of the machine. When tie lever 356 is pulled toward the rear of the machine, 1. e., to the left in Figure 12, shaft 350 is rotated to move the metal roll 306 forwardly and out of contact with the paper strip 22, so that the paper strip can be readily moved between rolls 304 and 306. A slot 358 is provided in the lever 356 to coact with a U-shaped guide and latch member 360 attached to the vertical frame plate I18 (see Figures 6 and 7), so that the roll 306 may be latched in release position to free both of the operator's hands for threading the new record strip into the machine.

The take-up roll 3| is detachably mounted in the machine so that when the record strip 22 is entirely covered with messages and wound onto this take-up roll it may be removed to keep these messages as a permanent record. One end of this take-up roll 3| is provided with a coupling 383, as shown in Figure 19, which coacts with a blade-like projection on the end of a pulley shaft 316which carries a driven pulley 310 suitably rotatably supported between the vertical frame plate I16 and a U-shaped bracket 311 secured thereto, as shown in Figure 6, driven by a paper wind-up motor, generally indicated at 380, as will hereinafter be described. The other end of the take-up roll 3| is provided with a pin 38I (see Figure 19), shown in dotted lines in Figure 6, which fits into a recess in the end of a rod 382 slidably mounted on the vertical frame member I18. This rod 382 is normally biased in a position to support the take-up roll 3| by means of a coiled spring 384 compressed between the frame member-I18 and a pin 386 passing through the rod 382. The otherend of, the rod 3821s attached to one end of a lever 390 which is pivoted at its other end to a projecting post 392 attached -to the end frame member I 18. A push rod 394 passes through'the end frame member I18 and is pivotally coupled to the center of the lever 390, as shown in Figure 6. Thus, when the push rod 394 is pushed toward the vertical frame member I18, rod 382 is moved to the right (in Figure 6) to withdraw rod 382 from pin 38I and thereby release the take-up roll 3|.

Incidentally, it is timely to mention at this point that the machine is so designed that all operationsrequired in inserting and threading spring latch member 366 at its upper end whereby it is detachably secured to the housing 6. A knob 368 is provided to facilitate the removal and replacement of this door 362. As can be more readily seen in Figures 6 and 9, immediately'inside of this door 362 at the rear of the machine are the U-shaped brackets 298 by,which the paper supply roll 294 is supported. Directly underneath these brackets 298 is the funnel-shaped paper slot 300 through which the record strip 22 may be slipped so that it passes upwardly over the platen 23, over the top of the machine, and back to the take-up roll 3| which is positioned directly above the supply roll 294. The take-up roll 3| is provided with a spring clip 318 to anchor the end of the record strip 22 to this roll 3|.

In order to be sure that lever 356 is unlatched after a new record strip has been positioned in the machine so that the pressure roll 306 will press the record strip 22 into contact with the paper driving roll 304 to render the paper shifting mechanism operative, the end of lever 356 is bent to form a projection 312 extending at right angles to this lever, and a cam-like projection 314 is attached to the rear door 362, as shown in Figure 7. Thus, whenever the door 362 is closed, the cam 314 presses against the projection 362 and lifts the slot 358 out of contact with the U-shaped latch member 360 so that lever 356 is 6 released under the tension of spiral spring 352,

thus permitting the pressure roll 306 to contact the paper strip 22 and press it against the drive roll 304 as shown in Figure 9.

As above-mentioned, a paper take-up or rewind is such that the paper winder motor 380 accelerates quickly with very small initial load and, as its speed increases, weights 315 bear more firmly on the inner surface of roll 3| to impart the desired steady torque to the roll for moving the record strip 22. In the event that the operator wishes to consult some previous message, this slipping connection between the faces of the weights 315 and roll 3| allows therecord strip 22 to be pulled through the door 30 in the top of the machine, thus unwinding some of the strip from the take-up roll 3|. After the operator has finished consulting the earlier message, the portion of therecord strip 22 thus pulled'from the telescriber may be rewound by pressing the pushbutton 32 at the front of the machine, thus energizing motor 380 to rotate take-up roll 3|.

motor 380 is mounted on the lower end of the vertical frame member I16, as shown in Figure 6. This motor is connected through a flexible coupling 396 to a'pulley 398 mounted on a pulley shaft 400-suitably rotatably mounted between the end frame plate I 16 and secured thereto. A coiled-spring type belt 404 connects this pulley 398 with pulley 318 associated with the take-up roll 3|. As will be hereinafter described, motor 380 is automatically energized each time the paper shifting mechanism operates to take up the slack in the record strip 22 as fast as the paper shifting mechanism moves the record strip past platen 23. The angular rotation of paper take-up roll 3| required for each spacing movement of the record strip 22 is relatively a U-shaped bracket 402 v In order to automatically shift an exact length of record strip 22'in each paper shifting operation and to automatically operate the rewind motor 380 during the paper shifting operation, an electrical contact structure is rovided, generally indicated at 406 and shown enlarged in Figures 7 and 8. This contact structure comprises a pair of metal roller contact members 408 and H0 mounted on but insulated from the paper roller drive shaft 330. Roller contacts 408 and 0 have grooves 4| 2 and 4, respectively, cut in their surface parallel to the shaft 330.

' Two sets of leaf spring contacts, contacts 6 and 4| 8 associated with roller contact 408, and contacts 420, 422 and 424 associated with roller contacts 0, are securedjogether in the usual manner in an insulated stack construction. These two sets of contacts are supported to the rear of platen 23 through intermediate bracket I12. These contacts are shaped as shown in Figures 7 and 8. Roller contacts 408 and 4| 0 are so secured to the drive shaft 330 relative to the leaf spring contacts 4| 8 and 422 that the ends of these leaf springs are simultaneously poised above their respective grooves H2 and H4 at substantially the same time, whereby the electrical connection between these leaf springs and roller contacts are made and broken in a manner hereinafter to be described.

small, and the torque required for reeling the l sure of friction'roller 804, and result in irregular or excessive paper shifting. A slipping connection is therefore provided within the roller itself as in Figure 19. A shaft 31|, suitably 'journaled at 313 and with its axis coinciding with the major axis of the roll 3|, carries at its inner end a pair of weights 315 guided in radially extending tubes 311. Thes weights 315 are faced with friction material 385 and are tensioned slightly against the inner surface of the roll 3| by a spring 319. The outer end of shaft 3.1| carries a coupling 383 shaped to receive the blade end of shaft 316 and form a support for one end of roll 3| through shaft 3H and journals 813. This construction The actual operation of this paper shifting mechanism can perhaps be best understood by reference to Figure 17 which shows the schematic wiring diagram of the entire transceiver. Therefore'its operation will be discussed in the following description of the operation of the entire instrument. 4

Referring to Figure 1'7, the transceiver may be considered as having four sections; a transmitter section 2, a receiver section 4, a power supply section, generally indicated at 5, and an external connection section, generally indicated at 1. The power supply section 5 (not illustrated in any of the other figures of the drawings) includes a constant voltage transformer 430, connected to any available A. C. supply, such as lines 426 and 428,

which is used to supply power to the message transmitting circuit elements of the telescriber. .Such a constant voltage transformer, though not essential, is desirable where the telescriber is to be operated on a supply line having any considerable fluctuation in voltage so that the voltages transmitted over the message transmitting circuit, 1. e.-, theright and left line circuits R-'| and L-|, will vary only in accordancewith the characteristics of the graphic characters beingtransmitted and not in response to fluctuations of the power supplyvoltage. The power supply section 5 also includes a second transformer 432 connected across the supply lines 426 and 428 to provide lower voltages for operating control signals and relays. In the embodiment shown, this transformer 432 provides two voltages through terminals 434 and 436. Terminal 434 supplies power for operating the pen-lifter circuit, and terminal 436 for operating interlock relay'II, busy" relay I30, and a receiver relay, generally indicated at 40I. This latter relay 40I, mounted in the base of the receiver portion 4 of the transceiver, as shown in Figure 5, controls the automatic operation of the paper shifting mechanism, energization of the pen-lifter mechanism, and operation of the signal buzzer. The master transmitting relay I32, the paper shifter motor 320, and the paper winder motor 380, are all operated from the full voltage of the power supply lines 426 and 428'. One side of the constant voltage transformer 430, the control voltage transformer 432, and all elements of the transcriber apparatus are connected to one side of the power supply line 426 which is connected to a ground circuit G. This ground circuit G is common to the entire telescriber system.

The connection portion 1 comprises the terminal board of the telescr'iber through which it is connected to four lines, R-I, L-I, P-I, and K-I leading to a distant transmitting station similar to the telescriber transceiver herein described; a ground line G, mentioned above, common to the entire system; and four lines R, L,

P, and K, leading to one or more distant receiving stations such as the receiver portion 4 of the transceiver herein described.

The low voltage ends of the right and left line inductive potentiometers Ill and H9 are each provided with a set of similar taps 442. The corresponding taps of these sets are-connected together, and a switch 444 is provided to selectively connect these taps to the ground line G. This arrangement permits the transmitter to be compensated so that the proper values of voltage are transmitted over lines L and R to the distance receivers regardless of the number of such receivers connected as a load across these lines.

When a message, or series of graphic characters, is to be transmitted to some distant receiver or receivers, signal push-button I8 is depressed. This closes a circuit from the terminal 434 of the signal transformer 432, through the contact 446 of the interlock relay I], through the contacts of the signal push-button I8, to the external line P, which in the-distant receiver is equivalent to the incoming line P-I in Figure 1'7. Line P, I is connected through contact arm I) of receiver relay 40I to contact and thence through an isolating condenser 430 to one side of the winding of the receiver signal buzzer I9, the other side of which is connected to ground line G. Thus, the signal buzzer of the distant receiver is actuated by pressing the signal push-button I0 to notify the operator at the distant receiver that a message is to be transmitted. The operator at the local station then moves the unison switch is to on position with the stylus 8. This closes the contacts of the unison switch I6 and completes a circuit to energize the winding of the transmitter master relay I32 which moves all of the contact arms b, d, g, m, and p of this relay from their normal positions, shown in Figure 17, to their alternative positions. Thus, operation of the transmitter master relay I32 opens the contacts a and b, in series with the winding of the interlock relay I1 and the busy" lamp 20, thus rendering the locking relay inoperative and preventing a distant station from looking the local transmitter 2 by transmitting a message to the local receiver 4. Likewise, connection is made between contacts c and d of relay I32 which connect the right and left line inductive potentiometers I I1 and H9 to the secondary winding of the constant voltage transformer 430, thus energizing these elements, so that two variable message voltages corresponding to the coordinates of the graphic characters to be transmitted may be developed between contact arms H4 and ground G. At the same time connection is made between contact arm g and contacts e and j of relay I32 to connect the variably positioned contact II4 of the right line inductive potentiometer II! to lines R-I and R leading to distant transmitter and receiver stations, and also to the right pen motor I50 of the local receiver 4. Similarly, connection is made between contact arm 12 and contacts n and o of relay I32 to connect contact arm II4 of the left inductive potentiometer Us to lines L-I and L leading to distant stations, and also to the left pen motor I52 of the local receiver 4. driving motors I50 and I52 of the local receiver 4 so that the pen 26 will make a record on the record strip 22 of the graphic characters being traced on the platen I4 by the stylus 8. Energization of relay I32 also makes a connection between contact arm 7' and contacts h and i. This energizes the local busy relay I30 through a.

circuit from terminal 436 of transformer 432 to line KI, and also energizes the receiver relay 40I. Theconnection to line K-.-I also energizes the busy relays at the distant transmitting stations to prevent them from sending a message to the local receiver during the time when the local transmitter is operating. Likewise, by connecting line K to tap 436 of transformer 432 by a connection in the distant receivers similar to the connection between contacts 12" and c" of the busy" relay I30 in the local receiver, their busy lamps, similar to lamp 20, and the energizing windings of their interlock relays, similar to windings 412 of relay I1, are energized to light these busy'- lamps to indicate that a signal is being transmitted to those stations and to lock those stations so that they cannot transmit during the time when the message is being sent from the local transmitter. Energization of the receiver relay 40l by closure of contacts 1 and h closes the contact between its contact arm b and contact a thereby closing the circuit to the pen-lifter magnet I54 so that it is in condition to be energized when a connection is made between contacts in and k of relay I32, as will be hereinafter described- Simultaneously, the circuit through contacts I) and c' to the local al buzzer I9 is broken so that it cannot. be operated while the local receiver is in operation. Further, energization of receiver relay 40I breaks the connection between its contacts e' and f and makes the connection between its contacts e' and d to operate the paper shifter mechanism, as will be hereinafter described. A further operation caused by the energization of the transmitting master relay I32 is to make a connection between its contact .arm m and contacts k and 1. This closes the circuit fromtap 434 on the signal transformer 432 throughthe platen switch to lines P-I and' P, thus, energizing these lines. The energization of line P-I energizes the pen-lifter magnets I54 of local receiver 4 through contacts a and b of relay 40I, while energization of line These last two connections energize the pen P energizes the pen-lifter magnets of the distant receiver or receivers.

As was described above, when the windings of the pen-lifter structure I84 are energized, its armature 218 is moved forward, thus moving penlifter bar 282 away from the platen 23 (Figures 6, 7, and 13) to lift the pen linkages 21 and 28 so that the pen 28 is lifted out of contact with the record strip 22. When the operator presses the stylus 8 on platen i4 to commence the trace of the characters to be transmitted, this separates the contacts I88 and I82 of the platen switch 88, thus opening the circuit to the local pen-lifter coil 212, as well as the circuit transmitting a message has been described, the

operation of the paper shifting mechanism can be more readily understood. The normal inoperative condition of the rotary contact structure 488 of this mechanism is that shown schematically in Figure 1'7. Inasmuch as there is no connection between contact springs M8 and 8 because contact spring 8 is poised over the groove 2 in roller contact 488, there is no connection through line 448 from line 428 of the- A. C. supply through paper winder motor 388 v to ground. Thus motor 388 is inoperative. Likewise, contact spring 422 is poised over groove 4 in roller contact 8. and contacts d and cf of receiver relay 48| are open, so that the circuit from the paper shifting motor 328 through line 448 to line 428 of the A. 0. supply is broken. Therefore, paper shifting motor 328 is deenergized. However, when the unison switch It is closed, thus energizing the transmitter master relay I32 closing contacts a and h to energize receiving relay 48l, connection is made between the line 428 of the A. C. supply, through line 448 andcontact arms to contact 11 of receiver r lay 48l. This closes a circuit through contact spring 424, rollercontact H8, and contact spring 428 to the paper Shifting motor 320. This energizes motor 828 causing the clutch mechanism 322 to engage and starts rotation of shaft 338 in the direction of the arrow in Figure 17. However, only a slight rotation of shaft 338 moves a roller contact 8 so that contact 424 is poised over the groove 4. This breaks the circuit to motor 328 and immediately stops rotation of shaft sao, thus leaving contact 424 in the position shown in Figure 18. In the meantime, contact 422 has made contact with the periphery of roll er contact 8, but, because receiver relay 48! is still energized and therefore the circuit between its contacts e' and! is broken, this cannot serve to energize motor 328. At the same time, contact arm 4l8'wil1 have made contact with the periphery of roller contact 488. but, inasmuch as roller-contact 488 has moved to the position shown in Figure 18, contact arm H8 is poised over the groove 4l2-so that at no time will the paper winder motor 888 have been energized during this operation. 1

When the operator at the local transmitter 2 has completed tracing the characters of his message on the platen l4,'or, if h has completely filled up. the platen and wishes to continue his message on a fresh area of the record strip 22 by advancing-the record strip by means of the paper shifting mechanism, he operates the unison switch l6. If he has completed his message, he

moves it to "off position and leaves it there, but if he wishes to continue, he merely moves it momentarily to off position and then return it to on" position. In either case, the transmitter master relay I32 is deenergized, at least momentarily, thus breaking the connection between its contacts 1 and h and so deenergizing the receiver relay 48!. Insofar as the paper shifting mechanism is concerned, this breaks the connection between contacts d' ande' and makes the connection between'contact e and f. Inasmuch as the contact structure 488 is now oriented, as shown in Figure 18, this completes the circuit fromthe line 428 of the A. C. supply, through line 448, contacts e and f of receiver relay 48l, contact arm 422, roller contact 8, and contact arm 428 to the paper shifting motor 328, thereby energizing this motor so that clutch 322 is once more engaged and shaft 338 starts to rotate. As above-mentioned, shaft 338 rotates the rubber-covered paper driving roll 384 against the paper strip 22 so that the paper strip starts to move from the supply roll 284 up over the platen 23. At the same time, rotation of the shaft 338 also rotates the roller contacts 488 and M8 and this rotation continues until contact arm 422 ridesoff of the periphery of roller contact 8 and is once more poised over the groove M4 in this roller contact, as shown in Figure 17. This automatically breaks the circuit to the paper shifter motor 328, thus deenergizing it and causing clutch 322 to immediately disengage. This stops the rotation of the paper drive roller 384 and therefore the motion of the record strip 22. During this operation, roller contact 488 is also rotating with the shaft 338, so that both contact arms 6 and M8 ride onto the periphery of contact 488, thus closing the circuit between these contacts. This energizes the paper winder motor 388 and causes it to drive the take-up roll 3! so that the paper strip, moved upwardly past the platen 23 by the paper drive roller 384, is wound up on the take-up roll 8|. At the same time that contact arm 422 rides oil of the periphery of contact roller H8, breaking the circuit to the paper shifter motor 328, contact arm 4| 8 also rides 01f of the periphery of upwardly a predetermined distance equal to the height of the platen 23, thus clearing the platen for the recording of another message. If, as above-mentioned, the operator wishes to send a further message, the paper shifting mechanism will repeat the cycle of operation just described.

If a message is to be received from a distant transmitter connected to lines R-l, L-i, P--l,

and K-i, the operation of the local receiver 4 is;

substantially identical with its operation when it was connected to the local transmitter 2 while the local transmitter was transmitting a message to distant receivers through lines R, L, P, 

